That all sounds good to me. I think one of the things holding us back right now is the ability to convert between interface types. At the moment, we only have functionality for Java2WSDL (no WSDL2Java, ESB to/from WSDL or Java), but once we get the other converters in place, it seems natural to let the user choose to convert the interface type when either promoting a service or generating a component from a composite service.
As for changing interface types, that should be possible at some point, but right now, things are in a bit of flux. We changed the controls used in the component and service creation wizards to allow the user to select the interface and interface type, but have not yet gotten around to updating the property sheets. In addition to this, there's a bit more work to be done to identify the interface types supported by a particular component (e.g. a bean component couldn't implement a wsdl or esb interface).